JPS6147909A - Production of synthetic resin optical transmission body - Google Patents

Abstract

PURPOSE:To obtain a synthetic resin optical transmission body having always the required and substantial degree of polymn. and stable performance by feeding back the surface temp. of a transparent gel object to a microwave transmitter and controlling the output of the transmitter so as to maintain the specified temp. thereof. CONSTITUTION:An extruder 1 extrudes a prepolymer liquid and while the liquid passes through a heating and forming means 2, the polymn. progresses and the liquid forms a transparent gel object 8. A monomer Mb contacts therewith in a diffusing device 4 so that the monomer Mb diffuses from the surface to the inside. The object 8 completes the polymn. while the object passes through a microwave irradiating vessel 5. The refractive index grade obtd. by the diffusion of the monomer Mb is fixed. The surface temp. of the object 8 is measured through a window 11 for measurement by a radiation thermometer 12. The measured signal and the set temp. signal from a temp. setting part 17 are compared and the microwave transmitter 15 is controlled by a control part 16 so that the always specified temp. of the object 8 is maintained. The always stable electric power (energy) is thus supplied to the object 8 regardless of the change in the properties of the object 8 and the variance in the place for placing the object 8 in the vessel 5 and the production of the above-mentioned transmission body with the stable performance is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a synthetic resin optical transmission body having a refractive index distribution in which the refractive index gradually decreases or increases in approximately proportion to the square of the distance from the central axis. Regarding the manufacturing method.

2. Description of the Related Art Conventionally, it has been known that a transparent rod-shaped body having a refractive index distribution in which the refractive index gradually decreases approximately in proportion to the square of the distance from a central axis acts as a convex lens.

In such an optical transmission body, the refractive index of the central axis is set to No.
Then, the refractive index N of a point at a distance of X from the central axis is (
A) It is expressed by the formula. Here, A is a positive constant (refractive index distribution constant).

N=No(1-2AX") (A) The light beam incident from one end of the rod-shaped body travels while meandering along the central axis. The periodicity of the meandering optical path is expressed by equation (B).

When the refractive index distribution is expressed by equation (C), the lens becomes a concave lens. Here B is a positive constant.

N=No(1+-BX”) (C) Patent application 1984-4
No. 7962 discloses that a polymer Pb having a refractive index Nb different from the refractive index Na of the reticular polymer Pa is added to a transparent gel body made of a reticular polymer Pa obtained by partially polymerizing a crosslinkable monomer Ma. Contacting the monomer Mb to be formed in a liquid phase or gas phase, and diffusing the monomer Mb from the surface of the object to the inside so that the inside of the object has a gradient that gradually decreases or increases from the surface to the inside. A method is described for producing a synthetic resin light transmitting body in which the refractive index changes continuously from the surface to the inside by polymerizing the synthetic resin by irradiating the resin with microwaves after or simultaneously with diffusion.

The problem that the invention aims to solve However, this method has the following drawbacks.

In other words, the physical properties (inductivity, etc.) of the transparent gel object to be polymerized change over time (as the polymerization progresses), and the state of introduction of the transparent gel object into the microwave irradiation container causes the transparent gel object to become microscopic. The energy received by waves changes, and even when processed under the same conditions (microwave output, processing time, etc.), the degree of polymerization varies greatly.
It is difficult to obtain a synthetic resin optical transmitter with stable performance if a sufficient degree of polymerization cannot be obtained or, conversely, the temperature of the transparent gel object may rise too much and cause it to turn yellow or burn. there were.

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems, and involves forming a network polymer (including copolymers) Pa (with Na as its refractive index). A monomer (including a monomer mixture) Ma is partially polymerized to form a transparent gel body, and the N
Polymers (including copolymers) having a refractive index Nb different from a Monomers forming Pb (including monomer mixtures)
Mb is brought into contact with the surface of the transparent gel object and diffused into the interior thereof, and the transparent gel object after or in the process of being brought into contact with the monomer Mb is irradiated with microwaves from the outside to diffuse it. In the method for producing a synthetic resin light transmitting body that promotes polymerization of monomer Mb and the transparent gel body, the surface temperature of the transparent gel body is measured, and the measurement signal is fed back to a microwave transmitter. Accordingly, the output of the microwave transmitter is controlled so that the surface temperature of the transparent gel object is always constant.

Function: With such a configuration, a synthetic resin optical transmission body with stable performance can be manufactured.

Example DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings.

Inside the extruder l, which is cooled by cooling water,
It is loaded with a viscous fluid prepolymer fluid used as a raw material for synthetic resin optical transmission bodies.

This prepolymer fluid maintains fluidity by prepolymerizing the monomer Ma until just before gelation. The prepolymer fluid is extruded from the extruder 1 and introduced into a Teflon tube 3 as a forming tube in a heated forming tool 2 .

Relatively high-temperature hot water and relatively low-temperature hot water are circulated in the upper and lower parts of the heating forming tool 2, respectively, and the temperature increases from the lower part to the upper part of the heating forming tool 2. There is a temperature gradient that gradually increases.

While passing through such a heating forming tool 2, the prepolymer fluid polymerizes and becomes a gel, forming a transparent gel object.

A diffusion device 4 is provided above the heating forming tool 2 .

Then, the transparent gel object that has come out of the heating molding tool 2 is brought into contact with the monomer Mb, and the monomer Mb is diffused into the inside from the surface thereof. The monomer Mb can be brought into contact with the transparent gel body in a liquid phase, a gas phase, or in the form of droplets. Due to this contact, the monomer Mb diffuses and moves through the contact interface of the transparent gel object toward the inside of this object, so that the monomer Mb has a gradient that gradually decreases from the contact surface to the inside of the object of the monomer sieve. Become. In contacting the monomer Mb with the transparent gel body, the temperature and time at which the monomer Mb can diffuse inside the body differs depending on each contact method, but the polymerization of the transparent gel body and the monomer weight does not proceed rapidly. It is carried out at a temperature of, for example, 5°C to 90°C for a period of 5 minutes to 3 hours.

The transparent gel body with the monomer weight diffused therein is provided above the diffusion device 4 in order to fix the refractive index gradient obtained by the diffusion of the monomer weight, make it a solvent-insoluble component, and improve weather resistance. It is introduced into a microwave irradiation container 5 for heat treatment. Reference numerals 6 and 7 are rollers that pull up the transparent gel object 8, which is a light transmitting body.

The microwave irradiation container 5 is provided with a gas introduction pipe 9 and a gas discharge pipe 10, respectively, and nitrogen gas or other inert gas such as helium, argon, etc. is introduced into the container 5 through these pipes 9 and 10. Or it is discharged from the container 5.

The microwave irradiation container 5 is provided with a temperature measurement window 11, and a radiation thermometer 1 is installed adjacent to the temperature measurement window 11.
2 is placed. The microwave irradiation container 5 is also provided with a microwave waveguide 13 , and this microwave waveguide 13 is connected to a microwave transmitter 15 via a matching device 14 .

The microwave transmitter 15 is controlled by a control section 16, and a measurement signal from the radiation thermometer 12 and a set temperature signal from the temperature setting section 17 are respectively input to the control section 16. ing.

Polymerization of the transparent gel object having the monomer weight diffused therein in the diffusion device 4 is completed while it passes through the microwave irradiation container 5, and the refractive index gradient obtained by the diffusion of the monomer Mb is fixed. At that time, in this example, the surface temperature of the transparent gel object 8 to be heat-treated is measured by the radiation thermometer 12 through the measurement window 11, and the measurement signal from the radiation thermometer 12 and the set temperature from the temperature setting section 17 are used. The microwave transmitter 15 is controlled by the controller 16 so that the temperature of the transparent gel object 8 is always constant by comparing the signals.

As a method of promoting the polymerization reaction of the monomer Mb inside the transparent gel body 8 and the network polymer Pa of this gel body, there are methods of heating from the outside with electric heat, hot air, etc., or irradiation with microwaves (for example, 2450 MHz) from the outside. Conventionally, heating methods using microwaves are known, but considering the uniformity of the degree of polymerization between the center and the outer periphery of the transparent gel object to be polymerized, the time required for polymerization, etc. A method using microwave irradiation is more preferred. However, the conventional method using microwaves has the following drawbacks.

That is, in general, the power by which microwave energy is converted into heat within an irradiated object is expressed by equation (D).

Here, P is the power converted into heat, f is the frequency of the microwave,
■ is the microwave electric field, ε is the dielectric constant of the material, tan δ
represents the dielectric loss angle of the material. Therefore, even if the microwave output is constant, if the ε or tan δ of the material changes, the heating efficiency of the material will change. Therefore, when trying to promote the polymerization of a transparent gel object, it is difficult to always promote the polymerization efficiently because tan δ also changes as the degree of polymerization of the transparent gel object changes. In addition, the strength of the microwave electric field is not uniform depending on the location in the microwave irradiation container, so the degree of polymerization acceleration varies depending on where the transparent gel object is placed in the container. In order to absorb it, it is important to match the impedance with the load.
If the matching is poor, the microwaves will not be absorbed and will return to the power source as reflected waves.Normally, a matching box (for example, a three-way stub) is used to match the load.
Therefore, even if the microwave output is always constant, unless the matching device is adjusted according to the physical properties (resistance, capacitance, etc.) of the transparent gel object, the degree of polymerization acceleration of the transparent gel object will change. This will result in fluctuations.

However, in this example, the surface temperature of the transparent gel object 8 to be polymerized is measured using the radiation thermometer 12, and the measurement signal is fed back to the microwave transmitter 15 to increase the surface temperature of the transparent gel object 8. By controlling the microwave output so that it is always constant, even if the physical properties of the transparent gel object 8 (ε, tan δ, resistance, capacitance, etc.) change, or the inside of the microwave irradiation container 5 Regardless of variations in the location where the object 8 is placed, stable power (energy) can always be supplied to the transparent gel object 8. As a result, it is possible to manufacture a synthetic resin optical transmission body that always has a necessary and sufficient degree of polymerization and has stable performance without variations.

The preferable surface temperature of the transparent gel body 8 is the monomer Ma,
Although it differs depending on the type of Mb, etc., it is usually controlled at an appropriate temperature of 60° C. to 150° C., and the treatment time is usually preferably carried out in a range of 5 minutes to 5 hours.

Further, the method according to the present invention is not limited to the continuous type optical transmission body manufacturing method as in the above embodiments, but can naturally be applied to conventionally well-known batch type methods.

In the present invention, the transparent solid object of the network polymer Pa to be brought into contact with the monomer Mb has undergone a certain degree of polymerization reaction, but the polymerization reaction has not yet been completed, and therefore contains components soluble in a solvent such as acetone. It is necessary to contain 10 to 95% by weight.

The presence of such solvent-soluble components promotes the diffusion of monomer Mb. When the content of the solvent-soluble component is less than 10!1%, the diffusion rate of the monomer Mb becomes low, the required contact time increases, and almost no refractive index gradient can be obtained, which is not preferable.

Further, if the content of the solvent-soluble components exceeds 95%, it is not preferable because the polymer has difficulty maintaining its solid form.

The monomer Ma used in the present invention includes two or more allyl groups, acrylic acid groups, methacrylic acid groups, or vinyl groups, or two types of allyl groups, acrylic acid groups, methacrylic acid groups, or vinyl groups. Monomer Ma having the above groups
can be used.

Examples of the monomer Ma suitable for the present invention include (1) allyl compounds diallyl esters such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, and diethylene glycol bisallyl carbonate; tri7lyl trimellidate;
Triallyl esters such as triallyl phosphate and triallyl phosphite; unsaturated acid allyl esters such as allyl methacrylate and allyl acrylate (2) Compounds R1 and R represented by R1-R1-R3
A compound in which either one of R1 and R3 is a vinyl group, an acrylic group, a vinyl ester group, or a methacrylic group; one of R1 and R3 is a vinyl group, an acrylic group, a methacryl group, or a vinyl ester group; and the other is any of the remaining three groups, where Rz can be selected from the divalent groups shown below.

(p- or m-isomer) (p- or m-isomer) (The above is 2A group) or CH.

(CHzCHgO) - CHtCHyo (m-
θ~20) (C1(z)p (P = 3~15n(
CHz)tH or H □C1h-CIIOtoGHz C-I CH3CHs (K host 0 to 20) (2B groups above) (3) A mixture of the monomers of (1) and (2) above, or a monovinyl compound, At least one of the five types of vinyl esters, acrylic esters, and methacrylic esters and the monomer (1) or (2) above (or mixture)
mixture with.

Further, as the monomer Mb, (4) a compound represented by S-butyl group, t-butyl group, (k-0~2) or (CHz CHtO)p CHt CH3(p-1
~6) (more than 4A groups) or (CFi)-F (a=1~6)CHz(CFt
)bH(b'=1~8)-CHtCHO0・CHz
CFz (CHt CHz O) cCFz CFz H(c-
1 to 4) -CHt CHt 0-CHz (CFz) -F(a
-1 to 6) CHz (CFz) a (CFz), g F(
d-1~2. 1-1 to 4) or Si(OCtHs)s (4B groups above) (5) CL=C1lOCRaHowever, R#: (CH2)rCF3 (f=0 to
2) (5A groups above) or -(cHz) * H (g-1 to 3) (k-0 to 2) (5B groups above) (6) As described in (4) and (5) above, Mixtures of monomers (1) to (3) above as monomers Ma, and (4) to (6) as monomer sieves can be combined, but in particular, as monomers Ma, the above By using monomers from the 2B group and using monomers from the 4B group or 5A group as the monomer sieve, an optical transmission body with extremely small chromatic aberration and excellent durability can be obtained.

In addition, in order to adjust the gelling state of the transparent gel object, the above (3)
), a method of adding a monomer having one unsaturated group to the crosslinkable monomer Ma, and CB r4. C
A method of adding a chain transfer agent such as C1* or mercaptans, or a method of using both in combination is effective.

Next, the present invention will be explained using specific experimental examples.

Diethylene glycol bisallyl carbonate in which 3.0% by weight of benzoyl peroxide (BPO) was dissolved (
CR-39) is prepolymerized by heating at 75°C for 65 minutes to make a prepolymer fluid, and this prepolymer fluid is put into the extruder 1 and passed through the molding tool 2 with an inner diameter of 4 mm and a length of 6. In 200 Tsuru Teflon tubes 3.
Hot water of 78° C. and 58° C. were fed continuously into the upper part of the forming tool 2 and the lower part thereof, respectively, at a constant flow rate of 3 xxo-" tag/min. A temperature gradient was created in which the temperature gradually increased from the top to the top.While passing through the Teflon tube 3 for about 30 minutes, the prepolymer fluid was formed into a transparent gel body with a diameter of 4 mm. It consisted of a transparent gel material.

This transparent gel body is pulled up by a pulling roller 6.7 at a constant speed of 0.52 cm/min, and the monomer ? After diffusing lb from the surface of the transparent gel object,
It was introduced into a microwave irradiation container 5 with an inner diameter of 230 mm and a length of 1 m.

The temperature setting unit 17 sets the surface temperature of the transparent gel object 8 to 110°C.
The surface temperature of the transparent gel object 8 is measured by the radiation thermometer 12, and the measurement signal is fed back to the microwave transmitter 15. Controlled output. At this time, the microwave output varied between 110W and 230W. The time during which the transparent gel object 8 passes through the microwave irradiation container 5;
That is, the processing time was about 192 minutes. In this way, diameter 4
1. A continuous rod-shaped body with a length of 3 m was manufactured, and a rod-shaped convex lens with a refractive index distribution constant A of formula (A) of 0.064 tm- was obtained.The average amount of components insoluble in acetone was 96.
At 4% by weight, the variation in the degree of polymerization in the longitudinal direction of the rod-shaped convex lenses was within 1%. It also had sufficient weather resistance.

A transparent gel object prepared in the same manner as in the above experimental example was introduced into the same microwave irradiation container 5 while being pulled up at the same speed, and the microwave output was kept constant at 170 W for treatment. The processing time was also about 192 minutes, the same as in the above experimental example. The thus obtained rod-shaped body with a diameter of 4mm and a length of 3m was a rod-shaped convex lens with a refractive index distribution constant A of formula (A) of 0.064 m-, but the acetone-insoluble component was present in the 1m-long portion at the tip. , it varies from 89.6% to 93.5% by weight, in the middle 1m part it varies from 93.8% to 96.8% by weight, and in the 1m part at the rear end it varies by 90.1% by weight.
It varied by 94.0% by weight. There were yellowing spots in the middle 1m section. In addition, parts containing 92% by weight or less of acetone-insoluble components had significantly poor weather resistance, and the refractive index distribution changed over time, causing performance problems.As described in detail, in the present invention, When a transparent gel object in which monomer Mb is diffused is heat-treated to complete its polymerization, the surface temperature of the transparent gel object is measured, and the measurement signal is fed back to the microwave transmitter to constantly maintain the transparent gel object. The output of the microwave transmitter is controlled so that the surface temperature of the

Therefore, it is important to always supply stable energy to the transparent gel object regardless of changes in the physical properties of the transparent gel object or variations in position within the microwave irradiation container. As a result, it is possible to manufacture a synthetic resin optical transmission body that always has a necessary and sufficient degree of polymerization and has stable performance without variations.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view of an optical transmission body manufacturing apparatus according to an embodiment of the present invention. In addition, in the symbols used in the drawings, 2------------------heat forming tool 4--
・・−・−・−・・Diffusion device 5−・−・・−−−−−・−1−−−−・−Microwave irradiation container 8・−・−−−−−・−・・・・Transparent gel object 12−・−・−・−・・Radiation thermometer 15・
−・・−・−・−・−・−−−−Microwave transmitter 1
6-・・・-・・-・−・・Control unit 17・----
-1...--...--Temperature setting section.

Claims (1)

[Scope of Claims] 1. Partial polymerization of the monomer Ma forming the network polymer Pa (whose refractive index is Na) to form a transparent gel object, and a polymer having a refractive index Nb different from that of Na. The monomer Mb forming the combined Pb is brought into contact with the surface of the transparent gel object and diffused into the inside thereof, and the transparent gel object after or in the process of being brought into contact with the monomer Mb is exposed to the transparent gel object from the outside thereof. In a method for manufacturing a synthetic resin light transmitting body in which microwave irradiation is applied to promote polymerization of the diffusing monomer Mb and the transparent gel body, the surface temperature of the transparent gel body is measured, and the measurement signal is is fed back to a microwave transmitter to control the output of the microwave transmitter so that the surface temperature of the transparent gel object is always constant. 2. The method according to claim 1, characterized in that the surface temperature of the transparent gel object is controlled within the range of 60°C to 150°C. 3. A measurement signal obtained by measuring the surface temperature of a transparent gel object is compared with a preset temperature signal, and a microwave transmitter is controlled based on this comparison, or The method described in Section 2.